Optimistic locking

Cédric explains optimistic concurrency in a nutshell. Neato! ;)

The hard disk storage access problem

Quoting Jim Gray again:

"We have an embarrassment of riches in that we're able to store more than we can access. Capacities continue to double each year, while access times are improving at 10 percent per year. So, we have a vastly larger storage pool, with a relatively narrow pipeline into it.

We're not really geared for this. Having lots of RAM helps. We can cache a lot in main memory and reduce secondary storage access. But the fundamental problem is that we are building a larger reservoir with more or less the same diameter pipe coming out of the reservoir. We have a much harder time accessing things inside the reservoir."

You really ought to read the whole interview. It's very interesting. :yes:

Of course, I don't really have a clue on that subject but as the discussion moves to access times (currently at 5 ms which is still very long!), I always wonder why those HD manufacturers don't put multiple heads on the arm... For example, if you'd put 4 heads on each arm, you'd have to move the arms 4 times less to access any cylinder on the disks. Considering disk rotation to the right block marginal (remember at 15 000 rpms an a half rotation only takes 33 µs!), that would almost divide access times by 4 instantly! :!:

I cannot even imagine this being a cost issue... so what :?: (ahem I mean, what am I missing... ;) )

mySQL & Oracle

(via Cédric) Jim Gray:

"Larry Ellison announced that Oracle is now running entirely on Linux. But he didn't say, "Incidentally we're going to run all of Oracle on MySQL on Linux." If you just connected the dots, that would be the next sentence in the paragraph. But he didn't say that, so I believe that Larry actually thinks Oracle will have a lot more value than MySQL has. I do not understand why he thinks the Linux problems are fixable and the MySQL problems are not."

Quote of the day - Concurrent development

The truth is that concurrent development is hard. Good SCM tools make it easier, but some people prefer to adopt processes which prevent complexity instead of using tools which help manage complexity.

-Eric W. Sink

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